Search for the modification of the properties of the $\omega$ meson in cold nuclear matter in the Hyperon-M experiment

The modification of the spectral function of vector mesons in nuclear matter is predicted in many theoretical models. However, the existing experimental results for testing these models are contradictory. Possible effects of the modification of the mass and width of $\omega$ mesons produced in the collisions of 7-GeV/c positively charged mesons with C, Be, Al, Cu, Sn, and Pb nuclear targets have been sought in the Hyperon-M experiment. The measured mass and width of $\omega$ mesons produced on the indicated nuclei are in agreement with each other with a high accuracy, which does not confirm the theoretical models predicting modification of the mass and/or width of the $\omega$ meson in nuclear matter.